Download A brief history of Genetics

A brief history of Genetics
1860s - G. Mendel described the basic principles of inheritance.
1866- E. Haeckel proposed that the nucleus contains the factors
necessary for heredity.
1871- F. Miescher described some of the chemical property of DNA
( C29H49N9P3O22). At that time proteins were supposed to be the
hereditary material.
1989 - Altmann names "nucleic acids“.
1903 - Walter Sutton proposes that chromosomes contain genetic
material.
1908 – All 4 bases in DNA now characterised, (incl. T & C) in
roughly equal amounts.
1909 - Enzymes found to be made from proteins. Archibold Garrod
proposes chromosomes affects enzymes.
1915 - Phosphate "backbone" proposed to connect DNA bases
together.
1927 - Ribose sugar associated with DNA characterised.
1928 - F. Griffith experiments with rough (R) and smooth (S) strains
of Streptococcus pneumoniae in mice.
1941 - Beadle and Tatum propose "one gene, one enzyme"
hypothesis.
1944 - Avery, MacLeod, McCarty show DNA is "transforming"
agent (e.g., genetic material).
1952 - Alfred Hershey & Martha Chase demonstrate that DNA
contains genetic material.
1953 - Postulation of a complimentary, double helical structure for
DNA (by Watson and Crick).
1955 - Chargaff & Davidson publish exhaustive set of three
volumes on "The Nucleic Acids", describing in great detail their
physical properties and characterisation.
1956 -Genetic experiments support hypothesis that genetic messages
of DNA are conveyed by its sequence of bp.
1958 - Meselson and Stahl demonstrate that DNA replicates semiconservatively.
Isolation of the first enzyme (DNA polymerase I) by A. Kornberg
1959 - Discovery of RNA polymerase.
1960 - Discovery of messenger RNA.
1961 - The triplet nature of the genetic code is discovered.
Monad and Jacob propose operon model of gene regulation
1965 - Appreciation that genes conveying antibiotic resistance in
bacteria are often carried on small bits of extrachromosomal DNA
(plasmids).
1966 - Establishment of complete genetic code.
1967 - Isolation of the enzyme DNA ligase.
1970 - Isolation of the first restriction enzyme.
1970 - Temin and Baltimore report the discovery of reverse
transcriptase in retroviruses.
1972 - Use of ligase to link together restriction fragments. First
recombinant molecules generated.
1973 - Eukaryotic genes are cloned in bacterial plasmids.
1976 - Retroviral oncogenes are identified as the causative agents of
transformation.
1977 - DNA sequencing becomes possible.
Interrupted genes are discovered and splicing of their transcripts is
inferred.
1978 - Production of first human hormone (somatostatin) using
recombinant DNA methods.
1979 - Cellular oncogenes are discovered by transfection.
1981 - Catalytic activity of RNA is discovered.
Transgenic mice and flies are obtained by introducing new DNA into
the germ line.
1983 - First version of "GenBank" created for storage of DNA
sequences.
1986 - Proposal of Intramolecular Triplex structure for certain purine
rich DNA sequences.
1989 - Polymerase Chain Reaction (PCR) technique first used.
1995 - First BACTERIAL genomes completely sequenced.
(Haemophilus influenzae and Mycoplasma genitalium).
1996 - Genome of first EUKARYOTE completely sequenced.
(Saccharomyces cerevisiae, 13,000,000 bp on 16 chromosomes).
1997 - Dolly the Sheep cloned.
E.coli genome sequenced.
2002 - Genome of Pasmodium (30 MB), Caenorhabditis elegans
(100 Mb), Arabidopsis thaliana (100 Mb), Drosophila
melanogaster (120 Mb), Mus musculus (300 Mb) have been
completely sequenced.
Actually, the Homo sapiens genome (3000 MB) is sequenced.
The Genomics and Post-Genomics age.
The discovery of the genetic material
The transforming principle is DNA (F.
Griffith experiments, 1928)
Streptococcus pneumoniae strains → R (rough) and S (smooth)
1944 – O.T. Avery, C. MacLeod and M. McCarty experiments
The DNA as transforming principle
I passaggi
fondamentali nei
protocolli
attualmente
disponibili sono: 12-3-5-6-7-10-11
Chemical composition
Prep. N.
C
H
N
P
37
34,27%
3,89%
14,21%
8,57%
42
35,50%
3,76%
15,36%
9,04%
DNA
34,2%
3,2%
15,32%
9,05%
The mechanics of inheritance
1952 - Alfred Hershey and Martha Chase experiments
with T2 bacteriophage in E. coli
T2 bacteriophages infecting an E.coli cell
1953 - Il modello proposto da Watson e Crick per la
struttura della doppia elica del DNA
Le principali tappe di una grande
scoperta
1) Scoperta del DNA (Miescher, 1869).
Caratterizzazione delle 4 basi azotate
(1903-08). Lo scheletro che connette le
basi azotate è formato da gruppi fosfato
(1915).
Il ribosio è associato con il DNA (1927).
James Watson and Francis Crick
2) Idrolisi del DNA, A/T = 1
C/G = 1 (Esperimenti di Chargaff).
3) Diffrazione ai raggi X.
I primi pattern di diffrazione risalgono al 1938 ma solo nel 1950 fu
possibile ottenere foto di diffrazione ad alta risoluzione nel
laboratorio di M. Wilkins.
Maurice Wilkins
Rosalind Franklin
2 periodicità → 3,4 Å e 34 Å
4) La struttura ad α elica delle proteine
(L. Pauling, 1951).
5) Elettrotitolazioni (basi legate da
legami idrogeno).
6) Il legame fosfodiesterico 3’--5’
(A.L. Todd, 1952).